1. Field of the Invention
The present invention relates to a light emitting diode, and particularly relates to a light emitting diode consisting at least in part of silicon carbide layers.
2. Description of the Prior Art
A light emitting diode consisting of layers of silicon carbide is known in the art which exhibits a mesa structure. This structure consists of a densely doped p-conductive substrate body consisting of silicon carbide, for achieving a low track resistance, having a surface on which a first epitaxially deposited layer consisting of silicon carbide with aluminum doping is grown. A second layer of silicon carbide, doped with aluminum and nitrogen so as to be n-conductive is disposed on the first silicon carbide layer. The actual mesa structure is formed not only by the two layers, but also by a significant portion of the substrate body, with portions of the substrate body surrounding the layered mesa being removed. One electrode is applied to the top-most layer of the mesa structure for supplying a bias current to the device. A cooperating electrode is formed by metallization of the side of the substrate body opposite to the side on which the mesa structure is formed.
Such a conventional silicon carbide light emitting diode emits blue light. The light is emitted in a direction radiating away from the substrate body and the mesa structure thereon, as viewed from the substrate body. Luminescent radiation is generated in the transition layer, but is emitted in the direction of the substrate and is largely absorbed in the densely doped silicon carbide substrate body. This lost portion of the radiation constitutes a significant portion of the total luminescent radiation generated at the junction.